Some very excellent cameras are constructed with pushbutton operated motor driven exposure and film advance mechanisms and also have detachable and interchangeable lens units that are secured to the camera body by bayonet or screw threaded attachments or the like. These cameras, particularly the through the lens reflex types, are ideal for underwater use if they can be suitably enclosed in a waterproof casing and, of course, it is desirable that such casing be easy and reliable to use, while at the same time being inexpensively constructed in a durable form.